It's a huge vector for abuse. The signal:noise ratio wouldn't improve at all.
Noone ever wants to go to xypdf.com for any reason unless they want to feel like they just had a stroke, how is (was? it made me stop using google except as a last resort in 2019) it often 3 of the top 5 results?
I wish I could just invert their SEO quality metric (there was a golden window around 2018 where you could just type -best into search engines that still respected subtraction to get only good reviews but sadly quality sites have fallen into line with the duck speak). I feel it's a pretty reliable indicator of garbage.
I’m also skeptical that all of Google’s enormous investment in ML and staffing is completely powerless to identify bad actors with atypical usage patterns. What seems far more plausible is that they’ve decided it isn’t costing them more in ad sales than it brings in. There are individual domains which would improve results by being blocked but they also pay for search ads so … unsolved grand challenge of computer science it is!
Isn't that exactly what people are complaining about here though? At least part o the problem with search results is that google seems powerless to recognize and remove useless bad actors (stack overflow copies, etc.) from their index.